This project will determine the effects of relatively low doses of commonly used and abused drugs on the probability of aggressive behavior in normal human volunteer subjects. Drugs to be studied include alcohol, benzodiazepines, codeine, and secobarbital. Aggressive behavior is brought under experimental control in a laboratory situation by provoking subjects which sets the occasion for aggressive responding which is maintained by specifying particular consequences such responding has upon subsequent provocations. By specifying a consequence for aggressive responses, we are able to maintain aggressive responding, gain more experimental control and study consequent events which maintain aggressive responding outside the laboratory. This project employs a methodology which has specific and unique advantages: (1) both aggressive and non-aggressive response options are available, (2) aggressive responses are operationally defined (as the presentation of an aversive stimulus to another person) and objectively recorded, and (3) the specificity of drug effects are considered by comparing effects on aggressive and non-aggressive responses. This experimental methodology will allow an assessment of the effects of drugs on different rates of aggressive responding maintained by escape from or avoidance of scheduled provocations. By specifying different consequences of aggressive responses, we can compare the effects of drugs on aggressive responses occurring in the absence and presence of provocation. In the natural environment, aversive provocation sets the occasion for both escape from the situation and aggressive retaliation directed at the source of provocation, i.e., counter-aggression. The third section of the project will examine the effects of environmental variables and drugs on response choices by subjects when both aggressive and escape options are available following provocation. These studies will provide information on how drugs representative of particular pharmacological classes may alter the choice of subjects exposed to aggressive provocation, i.e., retaliation-attack or escape-flight. The project will provide information on how commonly used drugs interact with environmental factors to alter the responses of normal human volunteers to aggression-provoking situations.